This invention relates to a process for process novel for the production of useful as a raw material in the manufacture of plastics such as in the reaction injection molding (RIM) of polyurea and the like.
Polyoxyalkylene polyamines find use as a raw material in the manufacture of polyurea elastomers and RIM as well as in hardening epoxy resins. It is known that when polyoxyalkylene polyamines are modified to have a plurality of secondary amino groups at the terminal ends of the molecule, the resulting products will exhibit excellent reactivity with polyisocyanate compounds compared with the corresponding primary polyoxyalkylene polyamines and, therefore, the resulting polyurea products may have excellent properties.
Aromatic diamines and xylylene diamines also find use in the polyurea RIM and the like. The modification of their primary amino groups to secondary amino groups also result in beneficial effects on the reactivity with polyisocyanates as well as properties of the resulting polyurea products.
One of prior art methods for producing secondary amine-terminated polyoxyalkylene polyamines is disclosed in Japanese Laid Open Patent Application (Kokai) Nos. 38425/1990 and 127425/1989. This method includes hydrogenolytic aminolysis of the corresponding polyoxyalkylene polyols with a primary amine. This method suffers from certain disadvantages in that the reaction takes place only under high pressure and high temperature in an autoclave in the presence of a catalyst such as Raney nickel. Another known method is disclosed in Japanese Laid Open Patent Application (Kokai) No. 153931/1990 and includes alkylation of the corresponding primary polyamines with alkyl halides. This method also suffers from certain disadvantages in that a portion of tile starting primary amine is necessarily consumed for binding the hydrogen halide by-product or an excess of acid-binding agent such as alkali metal hydroxides must be added. Besides, the conversion rate to secondary amino groups is relatively low and the alkylating agent is relatively expensive.
The alkylation method also find application to tile production of secondary aromatic diamines and xylylenediamines from tile corresponding primary amines as disclosed, for example, in Japanese Laid Open Patent Application (Kokai) Nos.311116/1990 and 251515/1990, respectively. In addition to various deficiencies as discussed above, alkylation of primary diamines of this type proceeds stepwise and one of primary amino groups may be alkylated only with difficulty once the other primary amino group has been alkylated. Accordingly, this method is utilized in practice for the product ion of asymmetric diamines in which one amino group is primary and the other is secondary.
All of the above discussed prior art methods generally give a secondary amine in which a second hydrocarbon substituent is an alkyl or aralkyl radical free of a functional group. In contrast with this, Japanese Laid Open Patent Application (Kokai) No. 251515/1990 discloses the Michael reaction of a polyamine with an acrylic or methacrylic monomer to convert low molecular weight , straight chain, aliphatic primary diamines or alicyclic primary diamines to the corresponding secondary diamines. The reaction products have a secondary amino group of which second hydrocarbon substituent has a functional group originating from the acrylic or methacrylic monomer. In our experiments, however, the secondary amine content of the products of this method is unsatisfactorily low particularly when the monomer is a methacrylic monomer.
Accordingly, a need exists for a secondary polyamine composition and a method of making the same which eliminate or ameliorate the deficiencies of the prior art compositions and methods.